This application is related to Japanese patent application No. HEI 11(1999)-120087 filed on Apr. 27, 1999 whose priority is claimed under 35 USC xc2xa7119, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
This invention relates to a plasma display panel (xe2x80x9cPDPxe2x80x9d) and a driving method of the same. More particularly, the invention relates to a plasma display panel having multiple built-in discharge cells as formed at locations partitioned by barrier walls or ribs in a discharge space within a panel, and also to a driving method thereof.
2. Description of the Related Art
Currently available PDPs are thin flat-panel display devices with enhanced on-screen image visibility and high-speed displayability while offering large-screen attainability. One example of such devices is an active-matrix driven areal-dischargeable PDP unit, which is typically arranged so that display electrodes forming a pair upon application of a drive voltage are laid out on the same substrate. The active-matrix PDP of this type is preferably adaptable for use in displaying full-color images by means of fluorescent materials.
One typical known AC-driven color PDP of the areal discharge type is designed in a way which follows. Multiple pairs of main electrodes for use in producing an areal discharge are horizontally disposed in substantially parallel to one another on one of spatially laminated substrates making up a panel at a pre-specified interval or pitch of reverse slit (non-discharge region) while providing on the remaining substrate a plurality of address (signal) electrodes used for address discharge production and multiple stripe-shaped ribs for physically partitioning a discharge space, adjacent ones of which sandwiches a corresponding one of the address electrodes therebetween, in substantially parallel in the vertical direction (a direction transverse to the main electrodes), wherein fluorescent layers of the three primary colorsxe2x80x94here, red (R), green (G), and blue (B)xe2x80x94are formed in a narrow elongate groove between adjacent ones of the ribs.
Note here that the areal discharge is sometimes called a xe2x80x9cdisplay dischargexe2x80x9d in view of the fact that such discharge is a main discharge for image display and may also be called a xe2x80x9csustain dischargexe2x80x9d because of the fact that it is a turn-on retaining discharge after addressing. Additionally, the main electrodes for areal discharge production are called xe2x80x9cdisplay electrodesxe2x80x9d since these are display discharging electrodes, or alternatively are called xe2x80x9csustain electrodesxe2x80x9d as they are the electrodes for use in producing the sustain discharge.
An on-screen image displaying operation of the PDP of this type is as follows. One sustain electrode of a sustain electrode pair is used as a scanning electrode to sequentially apply a voltage while during such voltage application applying a voltage to a desired address electrode causing an address discharge to take place between the address electrode and the one sustain electrode to thereby select a discharge cell to be turned on (this is generally referred to as xe2x80x9caddressingxe2x80x9d). Thereafter, by utilizing wall charge as has been formed during addressing, let a sustain discharge occur between paired sustain electrodes for an appropriate number of times that adequately complies with the intended luminance and color shade levels (thereby causing the discharge cell to turn on). To be brief, in case where one pixel consists of three separate RGB discharge cells, any desired color shade is reproducible by suitably determining what color of discharge cell is selected from RGB and how many times such cell is to be turned on; in this respect, the related art PDP is designed to produce the sustain discharge for a specified number of times as required to attain such reproducibility.
This gradation-of-shading displayability (color reproducibility) based on the control of the discharging number of such sustain discharge is typically attained by a method as will be discussed below. Subdivide a single frame (or a single field if one frame consists of two fields) into eight separate subfields, which are then subjected to weighting processing so that a relative ratio of these subfields"" luminance intensities becomes 1:2:4:8:16:32:64:128 for setting up the number of sustain discharge occurrences of each subfield. This makes it possible to perform brightness setup of 256 different levels with respect to each of the RGB colors, which leads to on-screen displayability of 2563 kinds of possible colors.
Incidentally, currently available PDPs suffer from a physical limitation as to shrinking or xe2x80x9cdownsizingxe2x80x9d of electrodes and ribs; due to this, the existing PDPs are encountered with a problem as to image quality reduction (low resolution) when employed for small-size screen displays when compared to traditional cathode-ray tube (CRT) display units, although the PDPs are adaptable for use with large-screen displays. To avoid this problem, several technical approaches to maximizing the required number of pixels (discharge cells) while minimizing requisite electrodes in number are proposed in recent years. One typical approach to achieving such maximal-pixel/minimal-electrode configuration is to employ a specific technique called an xe2x80x9calternate lighting of surfaces (ALiS)xe2x80x9d scheme for use with AC-driven color PDPs of the areal discharge type.
This scheme is a technique which replaces the one as has been designed to use two separate sustain electrodes per display line to visually display an image and which realigns such sustain electrodes at the equal pitch to utilize those available spaces between all the sustain electrodes as display lines. With this scheme, as shown in FIGS. 10A, 10B and 10C, one frame is subdivided into two fields consisting of an odd-numbered field and an even-numbered field for causing in the odd-numbered field a sustain discharge to take place at an odd-numbered line between sustain electrodes Xn, Yn (where xe2x80x9cnxe2x80x9d is a given natural number) (see FIG. 10A) while producing in the even-numbered field a sustain discharge at an even-numbered line between sustain electrodes Yn, Xn+1 (see FIG. 10B), wherein the odd-numbered and even-numbered lines are combined or synthesized together for constitution of a single on-screen image (see FIG. 10C). In the drawings, a dot-matrix display pattern of an alphabetical letter xe2x80x9cAxe2x80x9d is shown by way of example. A reference character A is used in this drawing to designate the address electrodes. Accordingly, this scheme permits the above-noted reverse slit portion to be used as part of an effective displayable region, which doubly increases the display lines in number without having to increasing the requisite number of electrodes involved.
This ALiS scheme requires the use of a panel structure shown in FIG. 11. More specifically, parallel sustain electrodes Xn, Yn are disposed in the horizontal direction on a display plane while parallel address electrodes A are laid out at right angles thereto in the vertical direction on the display plane, wherein ribs 31 are arranged between the address electrodes A in a way parallel to the address electrodes A. The exact number of such sustain electrodes is determined so that it is equal to the number of those discharge cells aligned in the vertical direction (vertical cell number) plus onexe2x80x94that is, the number of the sustain electrodes disposed is the display line number (2i) plus 1 (where xe2x80x9cixe2x80x9d is the maximum electrode pair number whereas the number of the address electrodes is the same as the number of those discharge cells in the horizontal direction (horizontal cell number).
The display lines include a first display line L1 as defined between the sustain electrodes X1 and Y1, a second display line L2 between sustain electrodes Y1 and X2, a third display line L3 between sustain electrodes X2 and Y2, a (2nxe2x88x921)th display line L2nxe2x88x921 between sustain electrodes Xn and Yn, and an n-th display line L2n between sustain electrodes Yn and Xn+1.
As shown in a partially enlarged diagram of FIG. 12, each of the sustain electrodes X, Y consists of a transparent electrode 32 comprised of a transparent conductive film made typically of indium-tin-oxide (ITO) and a bus electrode 33 formed of a metallic film made of Crxe2x80x94Cuxe2x80x94Cr or other similar suitable materials. In view of the fact that a sustain discharge is generated between the sustain electrodes X, Y between ribs 31, a discharge region between the sustain electrodes X, Y sandwiched between such ribs 31 becomes a discharge cell C.
With this scheme, when displaying an on-screen image, first use the sustain electrodes Y as scan electrodes to sequentially apply a voltage potential to the sustain electrodes Y1, Y2, Y3, . . . , Yn; during such voltage application, addressing is done in a way that applies a voltage to any desired address electrode A for production of an address discharge. Thereafter, utilize electrical charge formed during such addressing to produce a sustain discharge between sustain electrodes Xn, Yn (during an odd-numbered field) or alternatively between sustain electrodes Yn, Xn+1 (in an even-numbered field) for displaying any intended image on the screen.
In other words the ALiS scheme is inherently designed in such a way that scanning is done at the sustain electrodes Y in an odd-numbered field and, thereafter, let a sustain discharge take place between the sustain electrodes Xn, Yn (odd-numbered lines); after having again performed or re-performed scanning at the same sustain electrodes Y in an even-numbered field, produce a sustain discharge between the sustain electrodes Yn, Xn+1 (even-numbered lines).
With regard to displaying gradations of shading, the luminance-weighted sustain discharging. number setup scheme discussed previously is also employed therefor, which is the same as that used in the PDP of the type which makes use of two separate sustain electrodes relative to a single display line in the way stated supra.
The above-noted ALiS scheme is more excellent than that used for PDPs of the type using two sustain electrodes per display line in that the former is capable of displaying an increased number of display lines while using a less number of electrodes. Unfortunately, this advantage does not come as to a need to separately display odd-numbered display lines and even-numbered display lines in a way independent of each other during image displaying. From such a viewpoint, there has long been desired a PDP with a specific structure capable of efficiently displaying high-quality images with enhanced precision.
This invention has been made in view of the technical background, and its primary object is to provide a plasma display panel along with its driving method capable of displaying both the content being displayed at odd-numbered display lines and the content being displayed at even-numbered display lines at a time, by disposing the ribs diagonally while providing two different kinds of address electrodes including those for the odd-numbered display lines and the other for even-numbered display lines.
To attain the foregoing object, this invention provides a specific plasma display panel, which comprises a plurality of main electrodes laid out on an inside surface of one of a pair of substrates to have a stripe-shaped pattern with a distance defined between adjacent ones of the main electrodes, the distance corresponding to a display line for use as a discharge cell region; a plurality of sets of selection electrodes laid out on an inside surface of the other of the pair of substrates to have a stripe-like pattern in a direction transverse to the main electrodes, each set of the selection electrodes including a first electrode forming a first discharge cell at a cross point with a display line and a second electrode forming a second discharge cell at a cross point with the display line; and a plurality of ribs for partitioning a discharge space formed between the pair of substrates, each of rib being disposed extending from a cross point between an odd-numbered display line and the second selection electrode to a cross point between an even-numbered display line and the first selection electrode.
With the PDP structure of this invention, during discharge cell selection, it is possible by use of the first and second selection electrodes to simultaneously select both a discharge cell located on an odd-numbered display line and a discharge cell on an even-numbered display line at a time.
In addition, in discharge cell turn-on events, it is possible by using three main electrodes to simultaneously turn on both a discharge cell positioned on an odd-numbered display line and a discharge cell at an even-numbered display line at a time.
Use of the above inventive teachings permits occurrence of a surplus or xe2x80x9cidlexe2x80x9d time duration within the discharge cell turn-on time period, which in turn makes it possible to establish enhanced image displayability with an increased number of gradations of color shading, thereby enabling successful on-screen visualization of more crisp and vivid images high in precision and rich in shades of possible colors. In addition, lengthening turn-on time makes it possible to increase the luminance or brightness of displayed images, which in turn enables such images to increase in contrast on the screen.